试述骨髓瘤细胞的形态学特点。
参考答案：
骨髓瘤细胞有以下特点：①瘤细胞大小不一，一般较大，形态呈明显的多变性，多呈堆集分布。②瘤细胞呈圆形、椭圆形或不规则形，细胞核长圆形，偏位，核染色质疏松，排列紊乱，可见1～2个清楚的核仁。③胞质较丰富，量中等。染嗜碱性深蓝，或呈火焰状不透明，常含有少量天青胺蓝颗粒和空泡。④有些瘤细胞含红色粗大的包涵体、大量空泡及排列似葡萄状的浅蓝色空泡。⑤骨髓瘤细胞过氧化物酶染色呈阴性反应。
| Lichens may grow on the bark of a tree in a steaming tropical rain forest, on the bricks of big city buildings, on rocks in hot springs, on wind-swept mountaintops, and in the driest desserts. In the arctic, they provide the principal food for caribou, and they are one of the few plants that grow in Antarctica. They are pioneers, appearing in barren rocky areas and starting the formation of soil in which mosses, then ferns, and then other plants can take root. Lichens are a partnership of two plants — fungi and algae. The lichen body is made up of a network of fungal strands. In the upper layers of these grow groups of algae. The two organisms live together to the benefit of both, a relationship known as symbiosis. The fungi provide support, absorb water, and shelter the tender algae from direct sunlight. The algae carry on photosynthesis and provide the fungi with food. The algae can live independently and are recognizable as a species that grows alone. The fungi, on the other hand, cannot live apart from their partners. They can be placed in known classes of fungi but are unlike any species that lives independently. So definite are the form, color, and characteristics of these double organisms that for hundreds of years, they were classified as one. More than 15,000 "species" were named. If these organisms are classified as separate species, it is difficult to fit them into the existing system of classification. But if they are classified separately, these species of fungi seem rather strange. Lichens are a splendid example of the difficulties faced by taxonomists in classifying species. |
Which of the following is an example of symbiosis as it is described in Paragraph 2
A．Certain types of tall grass conceal tigers because of the tigers’ striped markings.
B．Fish called remoras attach themselves to sharks and eat the scraps of the sharks’ meals.
C．Mistletoe, a type of shrub, grows on trees and harms them by extracting water and nutrients.
D．Protozoa in the intestines of termites digest the cellulose that the termites eat, and their waste products nourish the termites.